Sash balance



y 0, 1965 I E. E. FOSTER 3,195,193

SASH BALANCE Filed April 8, 1963 FIG. 2 3

INVENTOR EDWIN E. FOSTER ATTORNEY United States Patent 3,195,193 SASH BALANCE Edwin E. Foster, 1801 Camp Craft Road, Austin, Tex. Filed Apr. 8, 1963, Ser. No. 271,089 3 Claims. (Cl. 20-52) This invention relates, in general, to window sashes, and, more particularly, to a spring balance for use in combination with a window sash which is slideable in a window frame.

Heretofore, various types of springs have been utilized for sash balances, but the same have proved, in usage, to have various inherent defects which have been traditionally accepted. Among such defects has been the difficulty of mounting such in window structures because of space limitations, since many prior devices comprise a relatively large number of parts integrated into a somewhat complex resultant construction; the problem of adapting balances for accommodating existing sashes; and the cost of providing and maintaining such balances, as many have demonstrated an undesired unreliability and, often, a short, effective life.

Therefore, it is an object of the present invention to provide a sash balance which is of marked simplicity, having an economy of parts; which parts are most readily mounted in operative relationship and which are so uniquely designed as to be accommodated within a spacing formed in an edge groove of a window sash of any predetermined thickness; and which balance is, thus, useable with window sashes of all types.

It is another object of the present invention to provide a sash balance which is most inexpensive to produce; which, should necessity arise, may be replaced in minimum time and at minimum cost; which may be utilized in conventional window constructions; which balances are invisible when in installed condition and which are most durable and reliable in usage.

The spring of the sash balance of the present invention comprises a length of flat, relatively thin spring metal ribbon which is torsionally resilient, being suitably formed as by a die for bias into helical formation; said strip being secured at both its upper and lower ends at the vertical side edges of a window sash, and being thus resistant to buckling on the return movement of the window, and being adapted for relative movement with respect to a follower as the sash is moved, which latter acts against the bias of said spring, so that the resiliency of the spring provides a force to balance the weight of the sash.

Other objects and details of the invention will be apparent from the following description, when read in connection with the accompanying drawing wherein:

FIGURE 1 is an isometric view of a sash balance constructed in accordance with and embodying the present invention and illustrating same in operative relationship upon a window sash, which latter is in window closed position.

FIGURE 2 is an isometric view of the sash balance in operative relationship upon a window sash, which latter is in partially open position.

FIGURE 3 is a transverse sectional view taken on the line 3-3 of FIGURE 1.

FIGURE 4 is an enlarged isometric view of the upper end of the spring and the associated parts.

Referring now by reference characters to the drawing which represents the preferred embodiment of the present invention, A designates generally a window sash having parallel side members 1, in each of which there is provided a groove or recess 2 opening laterally outwardly and extending throughout the length of the related side member 1. At the upper and lower outer edges of each side member 1 there is mounted an anchor plate 3, i, respectively, each having an outer portion projecting into "ice said groove 2. Anchor plate 4 in its projecting portion is provided with a narrow, slot-like aperture 5 axially parallel to the transverse axis of groove 2. Extending through said aperture 5 is the lower end of a thin, elongated, torsionally resilient strip 6, formed of suitable metal ribbon stock; there being means such as a pin 7 for preventing accidental dislogment of said strip 6 from anchor plate 4. It is to be particularly noted that aperture 5 and strip 6 are of complementary configuration, so that said latter is non-rotatable within the former.

At its upper end, strip 6 is secured to a support member 8 which extends freely through an aperture 33 in the projecting portion of anchor plate 3. Support member 8 is freely rotatable within aperture 9 for-purposes presently appearing. It is recognized that support member 8 may be of any suitable character, but in the embodiment shown, comprises a stern portion 10 of circular cross section passing through circular aperture 9, which latter is of slightly increased relative diameter; said stem being bifurcated at its lower end for receiving the upper end of strip *6 which is fixed therein as by a transverse pin 11. At its upper end, support member 3 is provided with a relatively enlarged head 12, which is disposed upon the upper face of anchor plate 3 for preventing displacement of said support member 8 therefrom.

Engageable with strip 6 and relatively movable lengthwise thereof is a follower 14 adapted for fixed securement upon the face of the window frame confronting groove 2. Follower 14 thus incorporates a mounting bracket portion 15 and a sleeve 16, which latter projects into groove 2 and is provided through its vertical extent with an opening 17 complementary to strip 6, which will travel through said opening 17 as sash A is raised and lowered. It is to be particularly noted that opening 17 lies substantially within the plane of the pane of glass'as at G in sash A.

Strip 6 is formed, as by application to suitable dies, into helical formation into which condition it is thus biased. The upper portion of strip 6 shown in FIGURE 2 illustrates the normal helical condition thereof.

To illustrate the usage of the present invention, reference will be made successively to FIGURES l and 2; said former illustrating sash A in downward or closed position and thus being considered a lower sash for movement upwardly into open condition. With sash A closed, follower 14 will be disposed at the upper end of strip 6, which strip shall be in straightened or non-twisted condition between said follower 14 and its lower end and thus being in a state of tension. As window sash A is moved upwardly and relatively past follower 14, the portion of strip a passing upwardly beyond follower 14 will be freed for return through inherent bias into helically twisted condition, while the portion below said follower 14- will remain in straightened or tensioned condition, as may best be seen in FIGURE 2. Thus, if sash A were raised to its full extent so that the lower end of strip 6 would be at follower 1d, strip 6 would be fully restored to its helically twisted condition. In effect, follower 14 in acting upon strip 6, overcomes the bias thereof, acting against the inherent resistance against untwisting. Therefore, strip 6 is torsionally resilient and the resistance to straightening in the strip itself will create a spring effect. It can be seen that by properly proportioning the spring relative to the weight of the sash, the sash may be accurately balanced so that it can be moved easily in either direction with a minimum of effort.

It is to be especially noted that by securement of strip 6 at its upper end, the same will not buckle during return movement of the sash and this feature represents a most decided critical step in the art of sash balances of this type. Furthermore, it will be noted that the lower end of strip 6 is fixed while the upper end through coaction with support member 3 is adapted for rotative mo ement to permit return of the portion of strip 6 above follower 14 to biased helical condition.

It will be further observed that the present invention comprises a marked simplicity of parts, in essence being only the flat, relatively thin strip 6 and the cooperating follower 14 which may be received in minimum space and which can be easily provided within a window sash. The components, thus, present a compact unit which can be easily installed in windows of all types whether of metal or wood, as well as in existing window constructions without necessitating structural modification thereof; Also, it will be noted that the sash balance of the present invention is completely invisible when'in operative position and does not diminish or mar an attractive window appearance.

Strip 6 may be as wide as groove 2 by virtue of the opening 17 of follower 14 being in the same plane as the window sash, so that the present balance can be used in windows having very narrow sashes.

Additionally,'and of considerable importance is the fact that strip 6 is relatively long and can be made quite flexible, whereby the same is capable of producing extremely low spring rate approximating a constant rate. Strip 6 presents an evenness in strain, so that reliability of action is achieved and stability in any preselected position of window sash A is accomplished.

It should be understood that changes and modifications in the formation, construction, arrangement, and combination of the several parts of the sash balance may be made and substituted for these herein shown and described Without departing from the'nature and principle of my invention.

Having thus described my invention, what I claim and desire to secure by letters patent is:

1. A sash balance comprising, in combination with a window having a frame and a sash reciprocally slideable in said frame, an elongated normally helically twisted thin strip, said strip being torsionally resilient for movement between flat uniplanar condition and twisted, helical formation, said strip being biased into helical formation, a follower having an opening complementary in shape to the cross section of said strip when the latter is in flat, uniplanar condition to be non-rotatable but longitudinally slideable relative to said strip for progressively causing an untwisting of said strip from helical formation into fiat, uniplanar condition when said sash is slidingly moved in one direction and forprogressively effecting releasing of said strip for return to biased helical formation from said flat, uniplanar condition when said sash is moved in the opposite direction, means securing said follower to said frame, one end of said strip being rigidly secured, against rotation, to said sash, an anchor member fixed on said sash remote from the point of securement of the said one end of said strip, said anchor member having an opening, a vertically presented strip support member extending freely downwardly in said opening and being freely rotatable therein, means provided on the upper end of said support member for limiting downward extent of said support member within said opening, and the other end of said strip being rigidly secured to said support member.

2. A sash balance as defined in claim 1 and further characterized by said strip support member being of circular cross-section and having a diameter relatively reduced with respect to the cross section of the opening in said anchor member for free extension of said support member through said opening, said support member having at its upper end a head portion of greater cross-section than the opening in said anchor member for abutment thereagainst to limit downward extension of said support member within said opening.

3. A sash balance as defined in claim 2 and further characterized by said support member being bifurcated at its lower end for receiving the strip member therein, and

means for fixedly engaging the received portion of said strip to said support member.

References Cited by the Examiner UNITED STATES PATENTS 346,110 7/86 Keyser 16l97 3,084,377 4/63 Foster 16197 HARRISON R. MOSELEY, Primary Examiner. 

1. A SASH BALANCE COMPRISING, IN COMBINATION WITH A WINDOW HAVING A FRAME AND A SASH RECIPROCALLY SLIDEABLE IN SAID FRAME, AN ELONGATED NORMALLY HELICALLY TWISTED THIN STRIP, SAID STRIP BEING TORSIONALLY RESILIENT FOR MOVEMENT BETWEEN FLAT UNIPLANAR CONDITION AND TWISTED, HELICAL FORMATION, SAID STRIP BEING BIASED INTO HELICAL FORMATION, A FOLLOWER HAVING AN OPENING COMPLEMENTARY IN SHAPE TO THE CROSS SECTION OF SAID STRIP WHEN THE LATTER IS IN FLAT, UNIPLANAR CONDITION TO BE NON-ROTATABLE BUT LONGITUDINALLY SLIDEABLE RELATIVE TO SAID STRIP FOR PROGRESSIVELY CAUSING AN UNTWISTING OF SAID STRIP FROM HELICAL FORMATION INTO FLAT, UNIPLANAR CONDITION WHEN SAID SASH IS SLIDINGLY MOVED IN ONE DIRECTION AND FOR PROGRESSIVELY EFFECTING RELEASING OF SAID STRIP FOR RETURN TO BIASED HELICAL FORMATION FROM SAID FLAT, UNIPLANAR CONDITION WHEN SAID SASH IS MOVED IN THE OPPOSITE DIRECTION, MEANS SECURING SAID FOLLOWER TO SAID FRAME, ONE END OF SAID STRIP VEING RIGIDLY SECURED, AGAINST ROTATION, TO SAID SASH, AN ANCHOR MEMBER FIXED ON SAID SASH REMOTE FROM THE POINT OF SECUREMENT OF THE SAID ONE END OF SAID STRIP, SAID ANCHOR MEMBER HAVING AN OPENING, A VERTICALLY PRESENTED STRIP SUPPORT MEMBER EXTENDING FREELY DOWNWARDLY IN SAID OPENING AND BEING FREELY ROTATABLE THEREIN, MEANS PROVIDED ON THE UPPER END OF SAID SUPPORT MEMBER FOR LIMITING DOWNWARD EXTENT OF SAID SUPPORT MEMBER WITHIN SAID OPENING, AND THE OTHER END OF SAID STRIP BEING RIGIDLY SECURED TO SAID SUPPORT MEMBER. 